Hepatic schwannoma： Imaging findings on CT, MRI and contrast-enhanced ultrasonography

A primary benign schwannoma of the liver is extremely rare and is difficult to preoperatively discriminate from a malignant tumor. We compared the imaging and pathological findings, and examined the possibility of preoperatively diagnosing a benign liver schwannoma. A 72-year-old woman was admitted to our hospital because of a 4.6-cm mass in the liver. A malignant tu- mor was suspected, and a right hepatectomy was per- formed. After this, the diagnosis of a primary benign schwannoma of the liver was made through pathologi- cal examination. Contrast-enhanced ultrasonography （CEUS） with Sonazoid showed minute blood flows into the septum and solid areas of the tumor in the vas- cular phase; most likely due to increased arterial flow associated with infiltration of chronic inflammatory cells. In the postvascular phase, CEUS showed contrast defect of cystic areas and delayed enhancement of solid areas; most Likely due to aggregation of sidero- phores. Because discriminating between a benign and malignant schwannoma of the liver is difficult, surgery is generally recommended. However, the two key find- ings from CEUS may be useful in discriminating ancient schwannoma by recognizing the hemorrhage involved in the secondary degeneration and aggregation of sid- erophores.